The study of epigenetics concerns the enormously complex mechanisms by which genotype gives rise to phenotype. It pertains to every aspect of development in virtually all organisms, and has been a good reminder that the essence of how genotype gives rise to phenotype does not, after all, reside completely in DNA. This application requests support for the 6th Gordon Research Conference on Epigenetics to be held at Holderness School, New Hampshire, August 7-12, 2005. Invited speakers are leading researchers working on prokaryotes, fungi, ciliates, plants, worms, insects, and mammals, and their presentations will cover some of the most fascinating and actively-studied areas of science today, including molecular and cellular memory, cellular de-differentiation, DNA asymmetry, DNA methylation, RNA interference, parental imprinting, X-chromosome inactivation, paramutation, ploidy, switching, environmental stress, genome defense systems, position effects, histone modifications, epigenetics of cancer, mammalian cloning, and stem cell development. These topics have direct relevance to human health, since disruptions in epigenetic programs underlie cancer, imprinted gene disorders such as Prader-Willi and Angelman syndromes, and mental retardation disorders such as Rett and ICF syndromes. The 2005 Gordon Research Conference on Epigenetics will provide a unique setting for researchers working on this broad spectrum of mechanisms and organisms to come together and exchange results and ideas. With a limited enrollment, ample time for both formal and informal discussions, and an eye toward promoting the careers of new investigators, the cross-disciplinary environment of this conference will foster the innovative thinking and novel collaborations that are critical for the success of researchers in the field of epigenetics.